This revised Phase II proposal describes the development of three simulation modules for training n therapeutic endoscopic retrograde cholangiopancreatography (ERCP): sphincterotomy, stone extraction, and stenting. The proposed work builds on a recently completed prototype simulator for diagnostic ERCP. A completed procedure description will be used to formulate a task analysis, from which we will develop didactic content and module layout. The proposed hardware focus on developing a tri-coaxial tracking system that provides haptics in translational and rotational axes, and simulating working channel force feedback associated with therapeutic tools. Therapeutic modules will require new organ and tissue models and renderings to represent various pathologies, case histories, and interventions. We also describe a more sophisticated model of fluid dynamics to simulate certain therapeutic manipulations, a particle-based system for simulating papillary changes during sphincterotomy, a standard electrical conductivity model for electrocautery, rigid body equations for stone dynamics, and a system of pre-defined fracture planes to simulate lithography. Clinical experts will provide formative evaluations, and a construct validity study will test whether the simulator can discriminate among experts, intermediates, and novices.